Halloween is the 2nd largest holiday after Christmas in terms of dollars spent, accounting for over $5 billion in sales.
Halloween also is recognized as the 3rd biggest party day after New Year's and Super Bowl Sunday.
One quarter of the candy sold for the entire year is purchased around Halloween (between September and November 10)
It was believed that ghosts came back to the earthly world and people thought that they would encounter ghosts if they left their homes. To avoid being recognized by these ghosts, people would wear masks when they left their homes after dark so that the ghosts would mistake them for fellow spirits.
Trick-or-treating is thought to have its origins in a European custom called souling where people would beg for "soul cakes."
Samhainophobia: Fear of Halloween